Calag Archive

Precise measurement of insecticide toxicity against house flies from various poultry ranches, dairies and cattle feed lots provided evidence of the presence of resistance roughly in proportion to the extent of insecticide use in each situation. The data indicate where changes to new insecticides are advisable, and illustrate how heavy reliance on insecticides over several years for fly control leads to gradual depletion of available insecticide resources.

In some almond producing areas of California, under-tree sprinkler irrigation is becoming increasingly popular for frost protection. Water applied for such frost protection during the early growth period has been observed to also have a marked effect on almond production that cannot be accounted for by frost protection alone. Among the effects-noted have been increased yield, larger kernel (meat) size, greater shoot growth, and delayed nut maturity. A project was started in 1968 to determine whether these previous observations could be experimentally substantiated, since only limited evidence has been available to show that these factors were related to early-season moisture supply.

On July 23, 1972 the National Aeronautics and Space Administration launched its first Earth Resources Technology Satellite (ERTS-1), using launch facilities at Vandenberg Air Force Base near Lompoc, California. From an orbital altitude of nearly 570 miles this unmanned satellite is photographing all cloud-free portions of California every 18 days and will continue to do so for an estimated 12-month period. Scientists of the University of California, in cooperation with those from the California Department of Agriculture and other state agencies, are studying the extent to which information extracted from such photographs can facilitate the management of California's agricultural resources. As illustrated by the cover photo, each “frame” of ERTS-1 photography covers more than 10,000 square miles. Nevertheless, when such a space photograph is enlarged, agricultural features as small as 100 feet across can be discerned (see pages 8 and 12). Many crop types and rangeland conditions can be inventoried, and land use categories can be recognized on such space photos when supplemented with only limited amounts of aerial photography, and direct on-the-ground observation. Results obtained to date indicate that careful interpretation of sequential space photography of the type currently being obtained by ERTS-1 can greatly facilitate the monitoring of crop development and land use change, thereby facilitating the management of California agricultural resources.

As one approach to growing a large number of lemon trees per acre, a trial was started in 1965 in Ventura County in which trees were trained on trellises. Due to exceptional growth and vigor of the Lisbon strain on C. macrophylla rootstock, three to four prunings were necessary each year. This excessive pruning in the case of treatment (1)—the heaviest pruned—caused a reduction in yield. Treatments (2) and (3), which were moderately pruned and trained, produced almost twice as much fruit as treatments (1) and (4) (the control). The low yields from the control trees were caused primarily from excessive wind. From the results of this trial it was difficult to justify the extra labor and costs of training and pruning necessary to commercially grow lemons on trellises.